Superabsorbent polymers (“SAP”) are polymers that can absorb liquids many times their own weight. Because the main characteristic of SAP is their ability to absorb and retain high levels of liquids, their predominant use is in hygiene products such as diapers, etc. As such, SAP plays an important role in everyday life.
SAP can be synthesized from a variety of monomers, although the most prevalent is acrylic acid. There are considerable differences between the major producers in their method of producing SAP. These differences result from the wide number of variables in SAP processes, including starting acrylic acid, initiator(s) used, crosslinker(s) used, reactor configuration, temperature and pressure of various equipment, as well many other factors. Typical SAP processes involve the copolymerization of acrylic acid, sodium acrylate, and a crosslinking agent to provide a minimally crosslinked polymer containing carboxyl and sodium carboxylate groups. Cross-linking during polymerization yields a networked polymer, which will not dissolve in water, and can absorb and retain water under low load.
As the demand for hygiene products continues with increased prosperity and an ageing population, the demand for SAP will continue. Furthermore, improvements in hygiene products are targeted towards improved SAP performance and thinner products, resulting in a decrease in the amount of SAP used per product.